Hemodialysis catheter apparatus

ABSTRACT

A catheter apparatus is provided for reducing blood clotting in connection with hemodialysis treatment. The catheter apparatus can comprise a first conduit defining an arterial lumen and a second conduit defining a venous lumen. Large staggered apertures can be provided in side walls of the conduits with at least one of the apertures having a cross-sectional area equal or greater than a cross-sectional area of one of the lumens. The catheter apparatus can further include first and second removable obturators adapted for axial insertion into the conduits and for occluding the apertures while so inserted. Advantageously, the obturators can wipe the apertures during removal, causing blood clots incident on the apertures to be dislodged from the apertures. Related methods for using the catheter apparatus in performing hemodialysis treatment are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/693,299 entitled “HEMODIALYSIS CATHETER APPARATUS” filed Jun. 23,2005, the entirety of the disclosure of which is expressly incorporatedherein by reference.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND

The present disclosure relates generally to catheters, and moreparticularly to catheters for use in hemodialysis treatment.

In the area of health care, it is often necessary to performhemodialysis treatment on patients that have malfunctioning or failedkidneys. Such procedures are typically performed on a periodic basis andcan require up to several treatments per week.

Hemodialysis treatments can sometimes require the insertion of acatheter into a patient in order to perform the treatment. However,because of the frequency of such treatments, it can become inconvenientto remove the catheter after treatment and re-insert the catheter forthe next treatment. This is especially true for procedures which requireinsertion of the catheter into the patient's groin area which can causesubstantial patient discomfort. As a result, it is often preferable toleave the catheter in place between treatments.

One primary problem associated with leaving the catheter in place is thetendency for blood to clot at openings of the catheter, therebyobstructing blood flow through the catheter during subsequent uses. Whenblood flow is obstructed, the time required to perform hemodialysis cansubstantially increase due to the greater length of time required toprocess a given volume of the patient's blood. This can result infurther inconvenience to the patient and increased health care expensesrelated to the operation of hemodialysis equipment for longer periods oftime.

One approach to removing such blood clotting involves the introductionof Heparin into the catheter after each use. Unfortunately, the use ofHeparin in conjunction with every successive dialysis treatment cancomplicate the administration of such treatments while simultaneouslyincreasing costs.

To reduce the possibility of clotting, prior art catheters are oftenadditionally limited in the number and size of apertures provided forreceiving the patient's blood and returning processed blood back to thepatient. Unfortunately, these limits on the apertures can also lead toprolonged dialysis time due to reduced blood flow rates.

Accordingly, there exists a need for an improved catheter apparatus andassociated methods that reduce blood clotting and promote high bloodflow rates in connection with hemodialysis treatment.

BRIEF SUMMARY

The present disclosure, roughly described, provides an improved catheterapparatus and methods associated therewith for reducing blood clottingand improving blood flow in connection with hemodialysis treatment. Thecatheter apparatus can comprise a first conduit defining an arteriallumen, the first conduit having proximal and distal ends, and a secondconduit defining a venous lumen, the second conduit having proximal anddistal ends. The second conduit and venous lumen can be shaped to belonger than the first conduit and arterial lumen.

A plurality of staggered first apertures can be provided in a side wallof the first conduit for receiving blood therethrough into the arteriallumen during hemodialysis treatment, with at least one of the firstapertures having a cross-sectional area equal or greater than across-sectional area of the arterial lumen. The first apertures maydecrease in size upon approaching the distal end of the first conduit. Aplurality of staggered second apertures can also be provided in a sidewall of the second conduit for expelling blood therethrough from thevenous lumen during hemodialysis treatment, with at least one of thesecond apertures having a cross-sectional area equal or greater than across-sectional area of the venous lumen. The second apertures mayincrease in size upon approaching the distal end of the second conduit.Furthermore, the first apertures may include at least two apertures ofdifferent sizes, and the second apertures may include at least twoapertures of different sizes. Finally, it is also contemplated that thesize of each of the first apertures may successively decrease uponapproaching the distal end of the first conduit, and that the size ofeach of the second apertures may successively increase upon approachingthe distal end of the second conduit.

The catheter apparatus can further include first and second removableobturators adapted for axial insertion into the proximal ends of therespective ones of the first and second conduits. In addition, theobturators can be fashioned to occlude the apertures while inserted intothe conduits. Advantageously, the obturators can be adapted for wipingthe apertures during removal of the obturators from the conduits. As aresult of the wiping of the apertures by the obturators, blood clotsincident on the apertures can be dislodged from the apertures.

The first obturator can comprise a first elongate sheath approximatelyequal in length to the first conduit and having a diameter approximatelyequal to a diameter of the arterial lumen. Similarly, the secondobturator can comprise a second elongate sheath approximately equal inlength to the second conduit and having a diameter approximately equalto a diameter of the venous lumen. The first obturator may lockablyengage the proximal end of the first conduit while the first obturatoris inserted into the first conduit, and the second obturator maylockably engage the proximal end of the second conduit while the secondobturator is inserted into the second conduit.

At least a portion of the first and second conduits can be implementedto share a common wall and comprise a substantially cylindrical elongatebody. In addition, each of the first and second conduits may define asubstantially semi-circular cross-section.

In another embodiment, a method for performing hemodialysis treatmentusing a catheter apparatus is provided. A distal end of the catheterapparatus can be inserted into a patient, preferably into a vascularstructure of the patient. First and second removable obturators can beaxially inserted into proximal ends of the respective ones of first andsecond conduits, of the catheter apparatus. While inserted into theconduits, the first and second obturators occlude apertures in sidewalls of the catheter apparatus. The obturators can be removed from theconduits, resulting in the obturators wiping the apertures and causingblood clots incident on the apertures to be dislodged from theapertures.

Conduits of the catheter device can be connected to hemodialysisequipment. Thereafter, blood from the patient can be allowed to flowthrough an arterial lumen of the catheter apparatus to the hemodialysisequipment for treatment, and blood treated by the hemodialysis equipmentcan be allowed to flow through a venous lumen of the catheter apparatusto the vascular structure of the patient. Following hemodialysistreatment, third and fourth removable obturators can be axially insertedinto the proximal ends of the respective ones of the first and secondconduits, with the third and fourth obturators occluding the apertureswhile inserted into the conduits.

These as well as other embodiments contemplated by the presentdisclosure will be more fully set forth in the detailed descriptionbelow and the figures submitted herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a catheter apparatus for use in hemodialysistreatment in accordance with an embodiment of the present disclosure;

FIG. 2 is a top view of distal ends of arterial and venous conduits of acatheter apparatus in accordance with an embodiment of the presentdisclosure;

FIG. 3 is a cross-sectional view of arterial and venous conduits of acatheter apparatus in accordance with an embodiment of the presentdisclosure;

FIG. 4 is a side view of a distal end of a venous conduit exhibiting aplurality of staggered apertures in accordance with an embodiment of thepresent disclosure;

FIG. 5 is a side view of a distal end of an arterial conduit exhibitinga plurality of staggered apertures in accordance with an embodiment ofthe present disclosure;

FIG. 6 is a cross-sectional view of an obturator partially inserted intoa conduit of a catheter apparatus in accordance with an embodiment ofthe present disclosure; and

FIG. 7 is a cross-sectional view of an obturator fully inserted into aconduit of a catheter apparatus in accordance with an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

FIG. 1 is a top view of a catheter apparatus 100 for use in hemodialysistreatment in accordance with an embodiment of the present disclosure. Asillustrated, the apparatus 100 can include a main body portion 105, avenous obturator 130, and an arterial obturator 170.

Turning first to the main body portion 105, an arterial conduit 150 isprovided for receiving blood from a patient through one or moreapertures at an open distal end 154 of the conduit 150, and passing theblood to dialysis equipment (not shown) through a proximal end 152 ofthe conduit 150. A venous conduit 110 is provided for receiving bloodfrom the dialysis equipment through proximal end 112 of the conduit 110and passing the blood back to the patient through one or more aperturesat an open distal end 114 of the conduit 110. In one embodiment,conduits 10 and 150 can be implemented using transparent PVC material.

The proximal end 112 of venous conduit 110 can be provided with a venousconnector 145 for connecting the conduit 110 to dialysis equipment andfor receiving a venous obturator 130, as further described herein.Similarly, the proximal end 152 of arterial conduit 150 can be providedwith an arterial connector 185 for connecting the conduit 150 todialysis equipment and for receiving an arterial obturator 170, asfurther described herein. In one embodiment, venous connector 145 can beblue in color and arterial connector 185 can be red in color. Asillustrated, the distal end 114 of conduit 110 extends beyond the distalend 154 of conduit 150 in order to reduce recirculation of bloodprocessed by the dialysis equipment from the venous conduit 110 backinto the arterial conduit 150.

Conduits 110 and 150 are physically separated into separate shafts atdistal ends 112 and 152. As the conduits 110 and 150 pass through anchor190, they are joined by a shared common wall and comprise asubstantially cylindrical elongate body extending from anchor 190 todistal end 154. Anchor 192 also comprises a plurality of suturing tabs192 useful for securing the main body portion 105 when in use. Main bodyportion 105 further comprises a cuff 195 encircling the body 105 forproviding frictional resistance to prevent inadvertent removal of thebody 105 from a patient.

FIG. 2 is a top view of distal ends 114 and 154 of venous and arterialconduits 110 and 150, respectively, of a catheter apparatus 100 taken atline 2-2 of FIG. 1. Venous conduit 110 and arterial conduit 150 includeside walls 115 and 155, respectively, as well as shared wall 197. Sidewall 115 and shared wall 197 of the venous conduit 110 define a venouslumen 120 for passing blood through the conduit 110. Similarly, sidewall 155 and shared wall 197 of the arterial conduit 150 define anarterial lumen 160 for passing blood through the conduit 150. Aperturesin side walls 115 and 155 of the conduits are also provided, as furtherdescribed herein.

FIG. 3 is a cross-sectional view of catheter apparatus 100 taken at line3-3 of FIG. 1. As illustrated, each of the conduits 110 and 150 andlumens 120 and 160 exhibit substantially semi-circular cross-sections.In one embodiment, the dimensions d0 (outside diameter of body 105), d1(thickness of shared wall 197), d2 (first lumen dimension), d3 (secondlumen dimension), R1 (first radius), and R2 (second radius) can beimplemented as 4.83 mm, 0.64 mm, 1.46 mm, 3.18 mm, 0.38 mm, and 1.78 mm,respectively. In addition, each of lumens 120 and 160 can be implementedhaving a cross-sectional area of 3.69 mm². However, it will beappreciated that such dimensions can vary in other embodiments.

FIG. 4 is a side view of a distal end of a venous conduit 110 taken atline 4-4 of FIG. 2. A plurality of apertures 125 (i.e. fenestrations)are provided in side wall 115 of conduit 110. The apertures 125 serve toexpel blood from the venous lumen 120 back to the patient duringhemodialysis treatment.

As illustrated, the apertures 125 can be offset from each other in astaggered orientation in order to reduce the likelihood of blockage ofthe apertures 125 during hemodialysis treatment. For example, if theside wall 115 of the catheter apparatus 100 is positioned against aninternal wall of a patient's vascular structure, such as an artery orvein, the staggered orientation can prevent at least some of theapertures 125 from being blocked by the internal wall. Although theapertures 125 are illustrated as being elliptical, it will beappreciated that alternative shapes can be used for the apertures 125including but not limited to non-elliptical or circular shapes. Inaddition, although three apertures 125 are illustrated in FIG. 4, itwill be appreciated that catheter apparatus 100 can be implemented withany number of apertures 125.

In various embodiments, some or all of the apertures 125 can be sized toexhibit a cross-sectional area equal or greater than a cross-sectionalarea of the venous lumen 120. Such sizing can significantly improveblood flow over prior catheters having smaller apertures, Moreover,blood clotting incident to the apertures 125 can be substantiallyeliminated through operation of obturator 130 as further describedherein. In one embodiment, dimensions d4, d5, and d6 of the apertures125 can be implemented as 3.05 mm, 1.53 mm, and 25.4 mm, respectively,with each aperture 125 having a cross-sectional area of 3.69 mm².However, it will be appreciated that such dimensions can vary in otherembodiments.

Additionally, it is also contemplated that the size of apertures 125 canbe implemented with the same or different sizes, such as with the sizeof each aperture 125 being larger in size than an aperture 125immediately to its left, resulting in increasing sizes for apertures 125closer to the distal end 114 of venous conduit 110. Such aconfiguration, in which the size of apertures 125 decreases toward thedistal end 114 of venous conduit 110, recirculation of blood processedby the dialysis equipment from the venous conduit 110 back into thearterial conduit 150.

FIG. 5 is a side view of a distal end 154 of an arterial conduit 150taken at line 5-5 of FIG. 2. A plurality of apertures 165 (i.e.fenestrations) are provided in side wall 155 of conduit 150. Theapertures 165 serve to receive blood into the arterial lumen 160 fromthe patient during hemodialysis treatment.

Similar to the discussion above with respect to FIG. 4, the apertures165 of FIG. 5 can also be offset from each other in a staggeredorientation in order to reduce the likelihood of blockage of theapertures 165 during hemodialysis treatment. Although the apertures 165are illustrated as being elliptical, it will be appreciated thatalternative shapes can be used for the apertures 165 including but notlimited to non-elliptical or circular shapes. In addition, although fourapertures 165 are illustrated in FIG. 53 it will be appreciated thatcatheter apparatus 100 can be implemented with any number of apertures165.

In various embodiments, some or all of the apertures 165 can be sized todefine a cross-sectional area equal or greater than a cross-sectionalarea of the arterial lumen 160. Such sizing can significantly improveblood flow over prior catheters having smaller apertures. Moreover,blood clotting incident to the apertures 165 can be substantiallyeliminated through operation of obturator 170 as further describedherein.

As discussed above with respect to the size of apertures 125, otherembodiments may be implemented with the size of apertures 165 being ofthe same or different sizes, such as with the size of each aperture 165being smaller in size than an aperture 165 immediately to its left,resulting in decreasing sizes for apertures 165 closer to the distal end154 of conduit 150. Alternatively, the size of apertures 165 can also beimplemented with different sizes, with the size of each aperture 165being smaller in size than an aperture 165 immediately to its right.However, it is contemplated that a configuration in which the size ofapertures 165 decreases toward the distal end 154 of conduit 150 maytend to reduce recirculation of blood processed by the dialysisequipment from the venous conduit 10 back into the arterial conduit 150.

Furthermore, with respect to the apertures 1251165, the apertures125/165 may each include a plurality of apertures, as shown in FIGS. 4and 5. For example, as shown in FIG. 4, apertures 125 may include atleast two apertures of different sizes. Further, as shown in FIG. 5, theapertures 165 may also include at least two apertures of differentsizes. Furthermore, the size of each of the apertures 125 maysuccessively increase upon approaching the distal end 114 of the conduit110, and the size of each of the apertures 165 may successively increaseupon approaching the distal end 154 of the conduit 150. Thus, if threeor more apertures 125/165 are used, each aperture 125/165 may have adifferent size than the other respective apertures 125/165, such as toallow the apertures 125/165 to respectively increase and decrease insize with each successive aperture 125/165. Other such configurationsand modifications may be implemented using the teachings herein in orderto reduce recirculation of blood processed by the dialysis equipmentfrom the venous conduit 110 back into the arterial conduit 150.

Therefore, the recirculation of blood processed by the dialysisequipment may tend to be further reduced when: 1) the size of eachaperture 125 is larger in size than an aperture 125 immediately to itsleft, resulting in increasing sizes for apertures 125 closer to thedistal end 114 of venous conduit 110; and 2) the size of each aperture165 is smaller in size than an aperture 165 immediately to its left,resulting in decreasing sizes for apertures 165 closer to the distal end154 of conduit 150.

As illustrated, apertures 165 can be distributed along a portion of sidewall 155 denoted by dimension d7. In one embodiment, dimension d7 can beimplemented as 10 cm. However, it will be appreciated that suchdimension can vary in other embodiments.

Returning to FIG. 1, as discussed, catheter apparatus 100 can comprise apair of obturators 130 and 170. Distal ends 134 and 174 of theobturators can be axially inserted into the proximal ends 112 and 152 ofrespective ones of conduits 110 and 150.

Obturators 130 and 170 each comprise flexible elongate sheathes 135 and175, respectively, each having substantially semi-circularcross-sections. Sheathes 135 and 175 can be sized so as to completelyfill lumens 120 and 160 and occlude apertures 125 and 165 while insertedinto conduits 110 and 150. Caps 140 and 180 attached to sheathes 135 and175 can be provided at the proximal ends 132 and 172 of the obturatorsfor securing the obturators 130 and 170 to connectors 145 and 185 ofconduits 110 and 150 while the obturators 130 and 170 are inserted.

The insertion of obturator 130 into conduit 110 can be furtherunderstood with reference to FIGS. 6 and 7. FIGS. 6 and 7 providecross-sectional views of an obturator 130 partially (FIG. 6) and fully(FIG. 7) inserted into a conduit 110 of a catheter apparatus 100 inaccordance with an embodiment of the present disclosure.

Referring to FIG. 6, obturator 130 comprises an elongate sheath 135attached to a cap 140 at the proximal end 132 of the obturator 130. Asillustrated, cap 140 comprises a ring portion 141 having a plurality oflocking members 149. The ring portion 141 is connected to a male luertapered portion 142.

Venous connector 145 comprises a plurality of locking members 148 and afemale luer portion 146. As illustrated, the female luer portion 146 canreceive the male luer portion 141 of cap 140. Venous connector 145further comprises recessed lead-in portions 147 for facilitating thereceiving of the proximal end 134 of obturator 130 into conduit 110.

Referring now to FIG. 7, obturator 130 is illustrated as being fullyinserted into conduit 110. While inserted, the male luer portion 142 ofcap 140 completely fills the female luer portion 146 of venous connector145, with locking members 148 and 149 engaging each other.

In addition, as illustrated at distal end 114, the sheath 135 ofobturator 130 occludes apertures 125 while inserted into the conduit110. Accordingly, it will be appreciated that obturator 130 can beinserted into conduit 110 after hemodialysis treatment has beencompleted and while the main body 105 of the catheter apparatus 100remains inserted in a patient. Due to the occlusion of the apertures 125by the obturator 130, blood clotting at the apertures 125 can besubstantially eliminated. When it is desired to perform dialysistreatment, obturator 130 can be removed from conduit 110. Upon suchremoval, a wiping action between the obturator 130 and apertures 125additionally removes any minor clotting incident at the apertures 125.Furthermore, subsequent flow of blood through the apertures 125 may alsotend to remove any minor clotting incident at apertures 125.

It will be appreciated that the insertion and removal of obturator 170with respect to conduit 150 can be performed in substantially the samemanner as described above with respect to obturator 130 and conduit 110.As such, obturator 170 can occlude apertures 165 and also perform awiping action therewith to remove clotting incident at the apertures165. Thus, the novel features discussed above with respect to obturator130 and conduit 110 may also apply for the obturator 170 and conduit150.

As discussed, catheter apparatus 100 is adapted for use in hemodialysistreatment. In operation, a substantial portion of the main body 105 ofthe apparatus can be initially inserted into a patient. In particular,the distal ends 114 and 154 of conduits 110 and 150 may be inserted intoa patient's vascular structure. If it is desired that hemodialysistreatment not be performed immediately, then obturators 130 and 170 canbe inserted into respective ones of conduits 110 and 150, and secured toconnectors 145 and 185 through locking members 148 and 149. The presenceof the obturators in the conduits 110/150 prevents the accumulation ofblood clots within the lumens 120/150 as well as on apertures 125/165and open distal ends 114/154 of the conduits 110/150.

When it is desired to perform hemodialysis treatment, then obturators130/170 can be removed from conduits 110/150, causing a wiping actionbetween the obturators 130/170 and apertures 125/165 to remove clottingincident at the apertures 125/165. Appropriate hemodialysis equipmentcan then be connected to connectors 145 and 185, thereby providing afluid path for the patient's blood to pass through lumens 120 and 150 ofthe conduits. During hemodialysis treatment, the sizing and placement ofapertures 125/165, as well as the removal of blood clots incidentthereto, allow for a high blood flow rate through the catheter apparatus100.

With particular regard to the wiping action between the obturators130/170 and apertures 125/165, the obturators may be formed to include avariable surface texture that enhances the wiping action. For example,the surface texture may be configured to include raised hair-likebristles. Thus, as the obturators 130/170 are removed, the bristles maycontact the apertures 125/165 and jostle loose any clotting incident atthe apertures 125/165. The surface texture may be formed in a variety ofmanufacturing processes and is not limited to bristles, but may includeother shapes and types of surface textures. In particular, the surfacetexture should be designed and configured to provide sufficientfrictional contact with the apertures 125/165 in order to provide properremoval of clotting. Further, the surface texture may be formedcontinuously along the length of the obturators 130/170 or selectivelyalong the lengths thereof, such as one or more rings, a helical pattern,etc. Thus, upon removing the obturators 130/170, the surface texture ofthe obturators 130/170 may further facilitate wiping action between theobturators 130/170 and the apertures 125/165 to remove clotting incidentat the apertures 125/165. In addition to removing the obturators 130/170with a single extraction stroke, the obturators 125/165 may beselectively moved axially back and forth or rotated past the apertures125/165 in order to enhance the removal of clotting from the apertures125/165.

After hemodialysis treatment is finished, a new set of sterileobturators 130/170 can be inserted into the respective ones of theconduits 110 and 150 and secured to connectors 145 and 185 throughlocking members 148 and 149. In this regard, it will be appreciated thatobturators 130/170 can be implemented as sterile, disposable items thatare replaced after each hemodialysis treatment. While inserted, thepresence of the obturators 130/170 in the conduits 110/150 prevents theaccumulation of blood clots within the lumens 120/150 as well as onapertures 125/165 and open distal ends 114/154 of the conduits 110/150between successive hemodialysis treatments. When it is desired tocommence hemodialysis treatment again, the new obturators 130/170 can beremoved in the manner previously discussed.

It will be appreciated that various aspects of the present disclosureprovide significant advantages over prior approaches to hemodialysiscatheters. The use of obturators 130/170 to reduce blood clottingremoves the need for costly repetitive applications of Heparin to thecatheter apparatus 100 before or after hemodialysis treatment. Inaddition, the reduced blood clotting at the apertures 125/165 allows forthe apertures to be sized with large cross-sectional areas, therebyimproving blood flow rates through the apparatus 100.

The foregoing disclosure is not intended to limit the present disclosureto the precise forms or particular fields of use disclosed. It iscontemplated that various alternate embodiments and/or modifications tothe present disclosure, whether explicitly described or implied herein,are possible in light of the disclosure. Where applicable, the orderingof various steps described herein can be changed, combined intocomposite steps, and/or dissected into sub-steps to provide featuresdescribed herein.

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 21. A catheter apparatus for use in hemodialysis treatment,the catheter apparatus comprising: a first conduit defining an arteriallumen and an arterial length, the first conduit having proximal anddistal ends, the arterial lumen having a first cross sectionalconfiguration that extends along a substantial portion of the arteriallength of the arterial lumen; a second conduit defining a venous lumenand a venous length, the second conduit having proximal and distal ends;a plurality of first apertures in a side wall of the first conduit forreceiving blood therethrough into the arterial lumen during hemodialysistreatment; a plurality of second apertures in a side wall of the secondconduit for expelling blood therethrough from the venous lumen duringhemodialysis treatment; and a first removable obturator adapted foraxial insertion in the proximal end of the first conduit, the firstobturator occluding the plurality of first apertures while inserted intothe first conduit, at least a portion of the first obturator includes atextured surface for dislodging blood clots incident on the plurality offirst apertures or in the arterial lumen.
 22. The apparatus of claim 21wherein the first and second cross sectional configurations are semicircular.
 23. The apparatus of claim 21 wherein the venous lumen has asecond cross sectional configuration along a substantial portion of thevenous length, and further including a second removable obturatoradapted for axial insertion into the proximal end of the second conduit,the second obturator occluding the plurality of second apertures whileinserted into the second conduit, at least a portion of the secondobturator includes a textured surface for dislodging blood clotsincident on the plurality of second apertures or in the venous lumen.24. The apparatus of claim 21 wherein at least a portion of the firstand second conduits share a common wall.
 25. The apparatus of claim 21wherein the plurality of first and second apertures are substantiallyelliptical.
 26. The apparatus of claim 21 wherein the plurality of firstand second apertures are substantially circular.
 27. The apparatus ofclaim 21 wherein at least one first aperture of the plurality of firstapertures defines a cross-sectional area equal or greater than thecross-sectional area of the first conduit, and at least one secondaperture of the plurality of second apertures defines a cross-sectionalarea equal or greater than the cross-sectional area of the secondconduit.
 28. The apparatus of claim 21 wherein the plurality of firstapertures are staggered in the side wall of the first conduit, and theplurality of second apertures are staggered in the side wall of thesecond conduit.
 29. The apparatus of claim 21 wherein at least a portionof the first and second conduits collectively comprise an elongate body,the apparatus further including a cuff circumscribing the elongate bodyand providing frictional resistance to prevent inadvertent removal ofthe catheter apparatus from a patient.
 30. The apparatus of claim 21wherein the venous length is longer than the arterial length.
 31. Theapparatus of claim 23 wherein the textured surfaces of the first andsecond obtruators include a plurality of bristles at distal end portionsthereof for wiping the plurality of first and second apertures duringremoval of the obturators from the first and second conduits to dislodgeblood clots incident on the plurality of first and second apertures. 32.The apparatus of claim 31 further wherein the first obturator furthercomprises a first elongate sheath approximately equal in length to thefirst conduit and having a diameter approximately equal to a diameter ofthe arterial lumen, and the second obturator further comprises a secondelongate sheath approximately equal in length to the second conduit andhaving a diameter approximately equal to a diameter of the venous lumen.33. The apparatus of claim 32 wherein the first obturator is configuredto lockably engage the proximal end of the first conduit while the firstobturator is inserted into the first conduit, and the second obturatoris configured to lockably engage the proximal end of the second conduitwhile the second obturator is inserted into the second conduit.
 34. Acatheter apparatus for use in hemodialysis treatment, the catheterapparatus comprising: a first conduit defining an arterial lumen, thefirst conduit having proximal and distal ends; a second conduit defininga venous lumen, the second conduit having proximal and distal ends; atleast three successive first apertures in a side wall of the firstconduit for receiving blood therethrough into the arterial lumen duringhemodialysis treatment, each successive aperture of the at least threesuccessive first apertures successively decreasing in cross sectionalarea in a direction toward the distal end of the first conduit; and aplurality of second apertures in a side wall of the second conduit forexpelling blood therethrough from the venous lumen during hemodialysistreatment.
 35. The apparatus of claim 34 wherein at least two of the atleast three successive second apertures have different sizes.
 36. Theapparatus of claim 34 wherein the plurality of second aperturescomprises at least three successive second apertures successivelyincreasing in cross sectional area in a direction toward the distal endof the second conduit.